Process of making linear shaped charge explosive devices



June 23, 1964 R. F. HATFIELD PROCESS OF MAKING LINEAR SHAPED CHARGEEXPLOSIVE DEVICES Filed Nov. 7, 1960 3 Sheets-Sheet 1 INVENTOR RichardF. Hatfield Fig.||

ATTORNEY June 23, 1964 R. F. HATFIELD PROCESS OF MAKING LINEAR SHAPEDCHARGE EXPLOSIVE DEVICES 5 Sheets-Sheet 2 Filed Nov. 7, 1960 Fig.4

Fig.3

INVENTOR Richard F.Hotfield BY W M X ATTORNEY June 23, 1964 R. F.HATFIELD 3,138,054

PROCESS OF MAKING LINEAR SHAPED CHARGE EXPLOSIVE DEVICES Filed Nov. 7,1960 5 Sheets-Sheet 5 INVENTOR Richard F. Hatfield BY W ATTORNEY UnitedStates Patent 3,138,054 PRGCESS F MAKING LiNEAR SHAPED CHARGE EXPLQSIVEDEVICES Richard F. Hatfield, Stanford, Califi, assignor to Jet ResearchCenter, Inc, Arlington, Tex, a corporation of Texas Filed Nov. 7, 1960,Ser. No. 67,817 3 Claims. (Cl. 861) This invention relates to a processof making tubular, linear shaped charge explosive devices.

Some forms of tubular, linear shaped charge explosive devices utilizingpreformed metal casings have been made heretofore by filling the casingwith a molten explosive material and allowing the explosive to solidifyin place. Even when using a flexible tubular casing, the extent to whichsuch linear shaped charge devices can be bent to conform to the shape ofan object to be cut is quite limited due to the brittle nature of mostcast explosive compositions. Breaks produced in the rigid cast explosivematerial by bending the casings are likely to cause cut-off of thedetonation wave as it proceeds down the length of explosive in thecasing with the result that only a portion of the length of the chargedevice is detonated.

Thus, the use of particulate explosive materials in filling linear,tubular shaped charge devices is desirable to achieve a flexible shapedcharge device that can be bent to cut irregular shaped objects and yetinsure the continuity of a detonation wave throughout the length of theshaped charge device. In fact, some of the high explosive materialspreferred for certain operations, such as Cyclonite and HMX, have suchhigh melting points that they cannot be conveniently cast but are bestused in the particulate form. It is well known in the art thatincreasing the apparent density of the explosive material in a shapedcharge device will produce an increase in the penetrating ability of thedevice. Achieving the desired degree of compression of a particulateexplosive material in situ in a preformed, elongated, tubular shapedcharge device has heretofore been a difiicult and time consumingoperation. Small increments of explosive material are usually pouredinto a pregrooved tubular casing which is closed on one end and thencompacted by a rod introduced through the open end of the tube. Auniform distribution of high density explosive material throughout thelength of the casing is very diflicult to obtain when using such packingmethods.

Therefore, it is an object of this invention to provide a process formanufacturing tubular, linear shaped charge explosive devices which havea uniform distribution of highly compressed, particulate explosivematerial throughout the effective length of the shaped charge devices.

Another object of this invention is to provide a process formanufacturing tubular, linear shaped charge explosive devices wherein alongitudinal groove is formed in the wall of a permanently deformable,generally tubular casing and the explosive material in the casing is compacted to the desired density simultaneously with the groovingoperation.

A further object of this invention is to provide a process formanufacturing tubular, linear shaped charge explosive devices whichutilizes an economical, readily available component for forming aunitary shaped charge casing and liner.

A still further object of this invention is to provide a process forforming a longitudinal groove in a permanently deformable, generallytubular casing of a shaped charge explosive device and compacting theexplosive material therein at the same time.

An additional object of this invention is to provide a 3,138fi54Patented June 23., 1964 process adapted for manufacturing tubular,linear shaped charge devices having various diameters.

A further object of this invention is to provide a process formanufacturing tubular, linear shaped charge explosive devices whichcontain a uniformly distributed, highly compressed, particulateexplosive material throughout the eifective length of the shaped chargedevice.

Still another object of this invention is to provide a process formaking a semiflexible, tubular, linear shaped charge device having aunitary shaped charge casing and liner which contains a uniformlydistributed, highly compressed, particulate explosive materialthroughout the effective length of the shaped charge device.

Briefly stated, the process of the invention includes providing a lengthof elongated, generally tubular casing having a longitudinallyextending, deformable wall portion being capable of taking a permanentset; forcing inwardly the longitudinally extending deformable wallportion of the casing to produce a longitudinal groove in the casingthereby reducing the internal volume of the casing; thereafter fillingthe grooved casing with particulate high explosive material; and forcinginwardly the longitudinally extending deformable wall portion of theexplosive filled casing along the longitudinal groove to produce alongitudinal groove of increased depth. Thus there is formed are-entrant shaped charge cavity linear from the deformable portion ofthe casing. Moreover, the particulate high explosive material iscompressed between the inner walls of the casing and is shaped toconform to the inner walls to produce a linear shaped charge having alower explosive weight per unit length and a deeper longitudinal groovecompared to a linear shaped charge produced as described in theforegoing steps with the exception that the casing is not pregrooved toreduce the internal volume thereof before being filled with particulateexplosive material.

Further in accordance with the invention, the steps of grooving thecasing or the steps of deepening the preformed groove may be carried outin a plurality of successive operations.

One form of apparatus for performing the process of the inventionincludes a supporting frame that supports a first shaft on which ismounted a backing wheel for rotation about its axis. The backing wheelprovides an annular groove continuous about its periphery. A groovingwheel is supported by a second shaft on the frame for rotation about theaxis of the grooving wheel. The rim of the grooving wheel is convex inaxial cross-section. The axes of the wheels are disposed substantiallyparallel to each other, and the groove of the backing wheel and the rimof the grooving wheel are disposed substantially in a plane. Means forrotating at least one of the wheels is provided.

The product produced by the process of the invention includes asemi-flexible, tubular, linear shaped charge unit which has anelongated, generally tubular casing having a longitudinal, re-entrantportion in the wall thereof. A body of compressed, particulatehigh-explosive material is contained within the casing. The explosivematerial conforms in shape to the inner walls of the casing, having beencompressed and conformed to the shape therein by inward deformation ofthat portion of the casing which provides the longitudinal re-entrantwall portion.

The process of the invention may be performed using variousinstrumentalities or even by hand, as will be explained more fullyhereinafter. One such instrumentality, which itself forms a part of thepresent invention, is the machine shown in the accompanying drawings.

In the drawings:

FIG. 1 is an elevational view of a typical machine for forming, inaccordance with the invention, linear shaped charge explosive devices;

FIG. 2 is a right side view of the machine of FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1;

FIG. '4 is an'enlarged cross-sectional view taken on line 4-4 of FIG. 3of the casing before grooving and the explosive therein beforecompacting;

FIG. 5 is an enlarged cross-sectional view taken on the line 55 of FIG.3, of the casing after grooving and the explosive therein aftercompacting;

FIG. 6 is a view in section taken along the line 66 of FIG. 1, showingin detail a means for adjusting the spacing between the grooving andbacking wheels;

FIG. 7 is an elevational view, partially in vertical medial section, ofa linear shaped charge exposive device made by the process of thepresent invention;

FIG. 8 is a side view of the linear shaped explosive charge device ofFIG. 7;

FIG. 9 is an'elevational view, partially in section, of a linear shapedcharge exposive device mounted on an object to be severed, showing onesystem for detonating the charge;

FIG. 10 is a left side view of the organization of FIG. 9; and

FIG. 11 is a cross-sectional view of the centering tube and guide screwof a typical grooving machine.

Referring now primarily to FIGS. 1, 2 and 3 of the drawings wherein atypical embodiment of a machine for manufacturing generally tubular,linear shape explosive charge devices is shown, the rectangular shapedframe has a pair of parallel, spaced apart side walls 21, 21 rigidlyjoined at their ends to a pair of spaced apart, parallel end walls 22,22 by welding or other suitable means. A base plate 23 is rigidlyattached, by welding or other'mean's, to the outside of the lower endwall. The base plate extends a substantial distance to one side of theframe to provide a means for attaching the machine to a work table. Theside walls provide a pair of generally rectangular, opposed openings 24in the upper one-half of the walls. In the lower one-half of the sidewalls, a pair of generally cylindrical, opposed openings 25 areprovided.

Roller bearing assemblies 26 are press fitted into each of the openings25 in the frame side walls. These hearing assemblies provide axialopenings therethrough in which is received a cylindrical shaft 27. Theshaft is mounted flush with the exterior surface of the left side walland projects a short distance out from the exterior surface of theright'side wall. A crank 28 is rigidly attached to the projecting end ofthe shaft 27 by means of a set screw 29. A backing or driving wheel 30is axially mounted centrally on that portion of shaft 27 extendingbetween the side walls 21. The driving wheel provides an annular groove31 continuous about the periphery and has integrally'formed collars 32,32 extending axially equidistantly from each side thereof. The drivingwheel is attached to the shaft 27, to rotate therewith, by set screws 33received in threaded transverse openings in the collars 32.

Referring now to FIGS. 2 and 6, the generally rectangular opening 24provided in each of the upper onehalf of the side walls 21 contains arectangular support block 34. The support blocks are constructed toprovide a snug, slidable fit with the vertical walls of the openings 24to permit vertical movement of the blocks within the openings 24. Eachof the support blocks'provides a; central opening 35 therethrough. Acylindrical shaft 36 extends between the side walls and the ends of theshaft are received in the openings 35 of the support blocks. The supportblocks are vertically positioned within the openings 24 by adjustingscrews 37, 37. Two threaded vertical screw holes 38 are provided in eachof the side walls to receive the adjusting screws 37. A pair'of springs39 extend between the lower edge of the support blocks and the bottomwall of the openings 24 to urge the blocks into engagement with theadjusting screws 37.

The spring ends are seated in shallow opposed recesses in the edge ofthe support block and the bottom wall of opening 24 to retain thesprings in position. A pair of retainer plates 40, 40 is attached to theoutside of each of the side walls by means of screws 41. These retainerplates are positioned adjacent to the openings 24 in the side walls andextend over the openings 24 a short distance on the verticalsidesthe're'of. The overlap provided by the retainer plates prevents thesupporting blocks 34 from working out of the openings 24. V

A grooving wheel 42 is axially mounted on shaft 36 centrally between theside walls 21 of the frame. An axial cylindrical opening is providedthrough the groov ing wheel to receive shaft 36. In one side ofthegrooving wheel an axial cylindrical counterbore 43 is provided toreceive a roller bearing assembly 44. A washer 45' on.

the shaft 36 fits into the counterbore to hold the bear ing in place.Sleeves 46, 46 and adjacent spacer washers 47, 47 are received on theshaft 36 on each side of the grooving wheel. The axial dimensions of thesleeves and washers aresuch that the rim of the grooving wheelispositioned centrally over the groove 31 in the backing wheel 30. Thegrooving wheel illustrated has, a rim portion that is generally V-shapedin cross-section. The peripheral surface at the terminus of the V isrounded slightly to prevent cutting the shaped charge tubular casingwhen forming the shaped charge device. Other rim shapes may be utilizedfor the grooving wheel, such as parabolic or hemispherical, to providethe contour desired for the groove in the linear shaped charge device.Atube straightener orcenteningdevice is mountedr-on'one edge of thesupport frame as can best be seen in FIGS. 1, 2 and 3. The centering orstraightener tube 48'is a thick walled, cylindrical section of metalproviding a cylindrical opening 49 therethrough. It is adapted to snuglyand slidably receive the tubing section or casing 56) for a tubular,linear shaped charge device and guide the casing into the groove 31 inthe backing wheel adjacent to the edge of the grooving wheel. A guidescrew 74 is threaded through the wall of the-centering tube 48 adjacentthe forward end. A forward-tube holder block 51, providing an openingtherethrough, receives the tube straightener and positions it in linewith the groove in the backing wheel. The block has'trunnions 52 on eachend received in openings provided in two bearing blocks 53, each ofwhich is attached by screws 69 to the side walls 21 of the frame. Thebearing blocks have slots 70 in their bases to receive the mountingscrews to permit vertical positioning of the forward end of the tubestraightener. A set screw 54 in the forward holder block locks'the tubestraightener in the selected position. A rearward tube holder block51a,like the forward tube holder block, supports the rearward end of thestraightener tube 48. A pair of brackets 55, 55 supports the rearwardtube holder block. Slots 71, 71 are provided in the feet of thebracketsfor attachment to the edge of the side walls of the frame'by screws 72,72 to permit vertical positioning of the rearward end of'the tubestraightener. The edges of'the frame side walls 21, 21 may be tapped ata-number of places, as shown in FIG. .1, to provide a variety ofpositions for mountingthe bearing blocks 53 and-thebrackets 55.

A gagev supportbracket 56 is attached by screws 73 to the top end wall22 of the frame. A dial-reading micrometer gage 57 is attached tov thesupport bracket. The gageis actuated by the upper end. of an extensionrod 58, which is slidably mounted in a vertical opening in the a eters.A number of backing wheels 30 may be provided, each having a peripheralgroove 31 of a different radius corresponding to the radii of commonlyavailable sizes of tubing. Separate backing wheels each having aperipheral groove radius to accommodate tubing in the sizes A in., /8in., /2 in., and /1 in. OD. are normally used. Referring to FIG. 1, itcan be seen that the backing wheel 30 can be readily changed byloosening set screws 33, sliding the shaft 27 out of the bearingassemblies 26, removing the grooving wheel and replacing it with one ofa different groove radius. The same grooving wheel 42 is used formanufacturing linear shaped charge units of the several diameters.

The process for manufacturing linear shaped explosive charge units ordevices utilizing the foregoing apparatus is as follows:

A section of tubing of suitable length is cut from a roll of tubing ofthe selected diameter and straightened to provide the casing 50 for thelinear shaped charge unit. Refrigeration grade, soft-drawn copper tubingis preferred for the casing, but other tubing capable of taking apermanent set, such as aluminum or lead, may be used. One open end ofthe section of tubing is closed by a strip of tape, or by insertingtherein a cork or rubber stopper (not shown). The tubing section is thensupported in the vertical position with its open end uppermost. Aparticulate detonating explosive material 59 (as shown in FIG. 4) isthen poured into the open end of the tubing section to substantiallyfill the section. It is advantageous, particularly when filling smallerdiameter tubing sections, to add the explosive slowly accompanied bygentle tapping on the tubing wall to prevent bridging of the explosiveand consequent formation of voids or spaces. The upper end of the tubingsection is then sealed in the same manner as the lower end. Referringnow to FIGS. 3, 4 and 5, a backing wheel 30, providing the proper sizedperipheral groove to accommodate the size of tubing used for the casing50, is mounted in the grooving assembly as hereinbefore described. Thescrews 37 are screwed out to permit the grooving wheel 42 to be raisedby springs 39 a sufficient distance to allow the casing 50 to passfreely underneath the grooving wheel edge. One end of the explosivefilled tubing section 50 is then inserted through the opening 49 in thecentering tube 48 to extend into the groove 31 opposite the rim of thegrooving wheel 42. The screws 37 are then screwed in until the edge ofthe grooving wheel 42 contacts the wall of the casing 50. The micrometergage 57 scale is then rotated to set opposite the pointer. The casing 50is then pulled back out of contact with the grooving wheel 42 and thebacking wheel 30.

The most satisfactory method of forming the groove 60 in the shapedcharge unit casing is to pass the casing through the grooving machine anumber of times, increasing the groove depth on each pass. Forming thegroove to its total depth in one pass through the grooving machine maycause the casing 50 to split longitudinally at the apex of the groove.The screws 37 are screwed in until the micrometer indicates that thegrooving wheel 42 has moved toward the backing wheel a fractional partof the distance desired for the total depth of the groove 60 in thecasing 50, for example, one-fourth the distance desired for the totaldepth. The explosive filled casing is then pushed into the groove 31 ofthe backing wheel and the crank 28 is rotated to draw the casing betweenthe wheels where the edge of the grooving wheel 42 forms a longitudinalgroove in the casing. When the casing has passed through the machine,the screws 37 are screwed in again until the micrometer indicates thatthe grooving wheel is lowered another incremental distance. The casingis inserted in the centering tube 48 and the guide screw 74 is screwedin until it projects into cylindrical opening 40 to lightly contact theedges of the grooved casing 50, as may be seen in FIG. 11. The guidescrew 74 prevents the casing from twisting or turning as it passesthrough the machine. If the casing is allowed to twist or turn, it willcause the groove 60 to have a twisted path around the casing. The casing50 is then run through the grooving machine again to increase the depthof the groove 60. This process is repeated until the final depth desiredfor the groove 60 is achieved.

The grooving machine is readily adjusted to produce shaped charge unitsin a straight or curved form. Curved shaped charge units may be madewith the groove 60 facing toward or away from the center of curvature. Acurved shaped charge unit having the groove 60 facing toward the centerof curvature is produced by positioning the brackets 53 and 55 so thatthe axis of the centering tube 48 intercepts the groove 31 in thebacking wheel 30 from above the horizontal. A curved shaped charge unithaving the groove 60 facing away from the center of curvature isproduced by positioning the brackets 53 and 55 so that the axis of thecentering tube 48 intercepts the groove 31 in the backing wheel 30 frombelow the horizontal. Increasing the angle between the axis of thecentering tube 48 and a horizontal line between the grooving and backingwheels will shorten the radius of curvature of the shaped charge unitand vice versa.

A modification of the hereinbefore described process for manufacturinglinear shaped charge devices has been developed which permits varyingthe weight of explosive material contained in a unit length of tubing ofgiven diameter. charge units made from the same diameter tubing may bewidely varied to fit the specific job at hand. The variation inexplosive weight per unit length of casing is controlled primarily bypregrooving the empty tubing section before it is filled with explosivematerial. A secondary control of the explosive density may be effectedby tamping the explosive into the pregrooved tubing section with atamping rod. The following table gives some specific data concerning theexplosive loadings per unit length when using the process utilizingpregrooving of the empty tubing section and tamping the explosive.

TABLE Explosive Load (Gm.) Per Unit Length (Foot) When Using 0.500" O.D.Soft Copper Tubing Weight of Ex- Weight of Ex- Pregroove Depth in Tubing(in) plosive Withplosive With out Tamping Tamping -l t) -l Thepregrooving of the empty tubing sections is handled in the same manneras the grooving of a tubing section containing explosive. The totalpregroove depth is achieved by making successive passes of the tubingsection through the grooving machine. Between each pass of the tubingthrough the machine, the grooving wheel is lowered slightly to increasethe depth of the groove in the casing. The successive passes arerepeated until the desired pregroove depth in the tubing section isreached. When making linear charges using 0.500 in. OD. copper tubing,it has been found that an increase in groove depth of 0.050 in. in thetubing section per pass is satisfactory. The grooving increment isdecreased when using smaller diameter tubing for the casing, andincreased when using larger diameter tubing. After pregrooving, thetubing section is filled with particulate explosive material. Theexplosive may be tamped as the tubing section is filled to increase theweight of explosive if desired. The explosive filled tubing section isthen passed through the grooving machine the additional number of timesrequired to achieve the final depth desired for the groove and, also, tofurther compact the explosive within the tubing section.

Thus, the cutting power of linear shaped The groove 60 in the casing 50of the linear shaped charge unit should not be made so deep thatsubstantially all the explosive material 59 is forced from between theapex of the grooved portion of the sidewall of the casing and theopposite side wall. Charges grooved too deeply do not form a properlyshaped jet and, consequently, have very low penetrating energy. 1

As stated hereinbefore, the process of the present in vention formanufacturing linear shaped charge devices may be carried out utilizinga number of different instrumentalities. For example, a machine pressmay be used which has a bed fixedly supporting the explosive filled,tubular casing and a powered V-shaped die extending the length of thecasing adapted to be moved into engagement with the supported casing topress a reentrant cavity in thecasing. Another suitable machine is onewherein the explosive filled, tubular casing is held fixed to a rigidsupport structure and a lateral force is applied to the casing by agrooving tool which is moved the length of the casing to form there-entrant cavity in the casing. The process is also capable of beingcarried out by hand using simple hand tools, such as a hammer and aproperly shaped punch, to produce the re-entrant cavity in the casingand to compress the explosive therein simultaneously.

For the purposes used herein, tubular casing is defined as including notonly circular tubular casing, but those of semi-circular, oval,elliptical, polygonal and other similar shapes. Also, the term includestubular casing of the shapes enumerated having a longitudinal grooveformed in a wall portion thereof prior to filling the casing withexplosive material and furtherdeepening the groove to compact theexplosive material.

Particulate explosive materials most suitable for use in preparing thelinear shaped charge devices are-desensitized Cyclonite or RDX(cyclotrimethylenetrinitramine) and desensitized HMX(cyclotetramethylenetrinitramine). The term particulate explosivematerial includes explosive material in a crystalline, granular or otherdiscrete small particulate state as distinguished from fused or castexplosive materials.

A description of an exemplary setup for cutting an object explosivelyusing a tubular, linear shaped charge device made according to thepresent invention follows.

A finished linear shaped charge unit 61, from which the sealed ends havebeen removed, is shown in FIGS. 7 and 8. The corks or other sealingmeans (not shown) used to seal the open ends of the casing 50 arenormally left in place until the linear shaped charge is ready for use.If cork or rubber stoppers are used to seal the easing ends, they aretightly held by the groove60 and cannot be easily removed. To prepare valinear shaped charge for detonation, the casing 50 is notched, using afile or other means, immediately to the rear of the cork and the end ofthe charge is broken off; The severed end of the charge provides a fresharea of explosive mate rial 59 flush with the edgeof the casing 56,which is desirable for good contact with the detonating means.

Referring now to FIGS. 9 and 10, an electric blasting cap 62 is heldendwise in direct contact with the explosive material on one end of thelinear shaped charge by means of strips of adhesive tape 63. Other meansmay be used to attach the blasting cap to the end of the shaped charge,such as a metal clip, adhesives or cements. The linear shaped chargescan be adapted for under water use by sealing each end and attaching adetonator with any suitable waterproof adhesive. A pair of electric leadwires 68 are attached to the blasting cap and extend to a safe, remotelocation where one leg wire is connected through switch 64 to one sideof a battery 65 and'the other leg wire is directly connected to thebattery. 'The linear shaped charge is supported by'brackets 66 toprovide the proper standoff distance from the target 67. These bracketsare conveniently made of strips of metal, such as brass or aluminum andare adapted to clip over the charge casing 50 to retain the charge 61 inposition with the groove 60 facing the target 67.

While the linear shaped charge devices shown are longitudinallystraight, it is to, be understood that curvilinear forms of the chargedevices are anticipated. As hereinbefore stated, one of the principalfeatures of the linear shaped charge devices produced 'by the process ofthe present invention is their adaptability to cut curved or irregularshaped objects. When a soft tubing is used for the charge casing, theshaped charge unit can easily be bent by hand or by using an ordinarytubing bender to the shape of most irregular shaped objects that it isdesired to cut.

It is to be understood that the apparatus, the process and the tubular,linear shaped charge explosive devices described herein are subject towide modification without departing from the scope and spirit of thisinvention. Accordingly, the specific embodiments here-in described anddepicted are to be considered as merely illustrative and not asrestricting the scope of the following claims.

I claim:

1. A process for producing a linear shaped explosive charge unit whichcomprises: providing a length of elongated, generally tubular casinghaving a longitudinally extending, deformable wall portion being capableof taking a permanent set; forcing inwardly said longitudinallyextending deformable wall portion of said casing to produce alongitudinal groove in said casing thereby reducing the internal volumeof said casing; thereafter filling said grooved casing with particulatehigh explosive material; and forcing inwardly the longitudinallyextending, deformable wall portionof said explosive filled casing alongsaid longitudinal groove to produce a longitudinal groove of increaseddepth, thereby forming a re-entrant shaped charge cavity liner from saiddeformable portion of said casing, compressing said particulate highexplosive material between the inner Walls of said casing and shapingsaid high explosive material to conform to said inner walls, to producea linear shaped charge having a lower explosive weight per unit lengthand'a deeper longitudinal groove compared to a linear shaped chargeproduced as described in the foregoing steps with the exception that thecasing is not pregrooved to reduce the internal volume thereof beforebeing filled with particulate explosive material. V

2. A process for producing a linear shaped explosivecharge unit as setforth in claim 1 wherein the step of forcing inwardly the longitudinallyextending, deformable wall portion of said explosive filled casing alongsaid longitudinal groove to produce a longitudinal groove of increaseddepth is carried out in a plurality of successive operations whereby thedepth of the groove is increased by each said successive operation.

3. A process for producing a linear shaped explosive charge unit as setforth in claim 1 wherein the step of forcing inwardly saidlongitudinally extending, deformable wallrportion of said casing toproduce a longitudinal groove in said casing, and the step offorcinginwardly the longitudinally extending, deformable wall portion of saidexplosive filled casing along saidlongitudinal groove to producealongitudinal groove of increased depth, are both carried out in apluralityof successive operations whereby the depth of thegrooveis'increased by each said successive operation.

References Cited in the file of this patent,

UNITED STATES PATENTS 2,589,541 Croson Mar. 18, 1952 2,638,323 BannonMay 12, 1953 2,826,235 Gudmestad Mar. 11, 1958 2,851,918 MacLeod Sept.16, 1958 2,966,822 Kistiakowsky et al Jan. 3, 1961 v FOREIGN PATENTS733,592 Great Britain July 13, 1955

1. A PROCESS FOR PRODUCING A LINEAR SHAPED EXPLOSIVE CHARGE UNIT WITHCOMPRISES: PROVIDING A LENGTH OF ELONGATED GENERALLY TUBULAR CASINGHAVING A LONGITUDINALLY EXTENSING, DEFORMABLE WALL PORTION BEING CAPABLEOF TAKING A PERMANETN SET; FORCING INWARDLY SAID LONGTIUDINALLYEXTENDING DEFORMABLE WALL PORTION OF SAID CASING TO PRODUCE ALONGITUDINAL GROOVE IN SAID CASING THEREBY REDUCING THE INTERNAL VOLUMEOF SAID CASING; THEREAFTER FILLING SAID GROOVED CASING WITH PARTICULATEHIGH EXPLOSIVE MATERIAL; AND FORCING INWARDLY THE LONGITUDINALLYEXTENDING, DEFORMABLE WALL PORTION OF SAID EXPLOSIVE FILLED CASING ALONGSAID LONGITUDINAL GROOVE TO PRODUCE A LONGITUDINAL GROOVE OF INCREASEDDEPTH, THEREBY FORMING A RE-ENTRATN SHAPED CHARGE CAVITY LINER FROM SAIDDEFORMABLE PORTION OF SAID CASING, COMPRESSING SAID PARTICULATE HIGHEXPLOSIVE MATERIAL BETWEEN THE INNER WALLS OF SAID CASING AND SHAPINGSAID HIGH EXPLOSIVE MATERIAL TO CONFORM TO SAID INNER WALLS, TO PRODUCEA LINEAR SHAPED CHARGE HAVING A LOWER EXPLOSIVE WEIGHT PER UNIT LENGTHAND A DEEPER LONGITUDINAL GROOVE COMPARED TO A LINEAR SHAPED CHARGEPRODUCED AS DESCRIBED IN THE FOREGOING STEPS WITH THE EXCEPTION THAT THECASING IS NOT PREGROOVED TO REDUCE THE INTERNAL VOLUME THEREOF BEFOREBEING FILLED WITH PARTICULATE EXPLOSIVE MATERIAL.